1. Field of the Invention
The present invention relates to a high strength aluminum alloy casting having superior mechanical properties, a high strength aluminum alloy casting including a neutralizing casting defect element for increasing the strength (hereinafter also referred to as an “NCDE”), and parts made from this high strength aluminum alloy casting such as a scroll for a compressor for an air-conditioner, a vane rotor of a valve timing regulating device, and a housing of an antilock braking system. Further, the present invention relates to a method of production of the above high strength aluminum alloy casting, a method of production of a high strength aluminum alloy casting including a neutralizing casting defect element, and a method of production of parts made from this high strength aluminum alloy casting such as a scroll for a compressor of an air-conditioner, a vane rotor of a valve timing regulating device, and a housing of an antilock braking system.
2. Description of the Related Art
As prior die casting technology relating to increasing the strength of a scroll made of an aluminum alloy casting, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 9-256127, there is a method of water cooling or age hardening a cast or die-cast scroll die casting immediately after releasing it from the die. That is, the method of production of the die casting in Japanese Unexamined Patent Publication (Kokai) No. 9-256127 adjusts the contents of the precipitation hardening elements Cu and Mg in the elements contained in the aluminum alloy and performs water quenching and age hardening so as to improve the state of precipitation of Cu and Mg and enhance the strength of these alloys. Further, in the method of production, it was confirmed that the tensile strength, yield strength, and fatigue strength of the die castings were enhanced, but these aluminum alloy die castings have casting structures formed as meshes, so were inferior in properties compared with aluminum alloy die castings solubilized and age hardened to make the eutectic Si spherical (T6 treatment).
Further, Japanese Unexamined Patent Publication (Kokai) No. 2000-192180 discloses a die casting of aluminum alloy having a chemical composition resembling the above and a method of production of the same. This method of production tries to improve the strength of the die casting by suppressing the amount of gas included in the die casting of the aluminum alloy and solubilizing the alloy. However, aluminum alloy scrolls provided in air-conditioners in recent years have changed along with the higher efficiency of air-conditioning and changes in the refrigerant used. With just the improvements of the method of production described in Japanese Unexamined Patent Publication (Kokai) No. 2000-192180, it is not possible to satisfy the design requirements of aluminum alloy scrolls.